Effect of cytokines on expression of Na⁺/Ca²⁺ exchanger (NCX) protein isoform NCX1 in human airway smooth muscle (ASM).

<p>Under normal conditions, human ASM cells expressed only the NCX1 isoform, but not NCX2 or NCX3 (which were detected in positive controls, however). Transfection with small interference RNA (siRNA) targeting NCX1 resulted in significant reduction in protein expression (120KDa), while the vehicle (Lipofectamine) or scrambled siRNA (neg siRNA) had no significant effect. Overnight expression of ASM cells to the pro-inflammatory cytokines tumor necrosis factor alpha (TNFα) and interleukin-13 (IL-13) for 24 h substantially enhanced NCX1 (120KDa) expression compared to controls not exposed to cytokines. The other NCX isoforms remained undetectable. α-Smooth muscle (αSM) actin was used as loading control. Values are means ± SE (n = 5). * indicates significant NCX1 siRNA effect, # significant cytokine effect (p<0.05).